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We have carried out quasielastic neutron scattering measurements on liquid tellurium (l-Te) at 460°C, and inelastic neutron scattering measurements on trigonal tellurium (t-Te) at 400°C, supercooled l-Te at 400°C and l-Te at 467°C. The quasielastic scattering peak is comparatively narrow at momentum transfer Q =2.0 A -1 where the first peak of the static structure factor is seen. The vibrational density of states (V-DOS) of supercooled l-Te has a three-band structure similar to that of t-Te, indicating that the chain structure is preserved in the liquid state. The V-DOS of l-Te changes remarkably with temperature, which strongly demonstrates the modification of chain structure in the liquid state.

We have recently developed a high resolution quasielastic neutron scattering spectrometer LAM-80ET by applying mica crystals as analyzers and achieved a resolution of Δ e =1.3 µeV using the 002 reflection. Single chain dynamics of polyethylene has been investigated below and above the melting temperature T m (=135°C) to show the feasibility of the mica 002 reflection as the analyzer. It was found that elastic scattering intensity from polyethylene decreases very steeply around the T m . Quasielastic broadening in the spectrum at Q =0.082 A -1 is observed only above 210°C, which is 75°C higher than the T m . From the analysis of the spectra by a curve-fitting method, the width of the quasielastic component was evaluated to be 1.8 µeV at 250°C and the activation energy of the width to be 34 kJ/mol.

The hydrogen vibrational modes in KH 2 PO 4 (KDP) were, for the first time, clearly observed by incoherent inelastic neutron-scattering measurements over a wide energy range; some small changes in the spectra were found around the transition temperature. By single-crystal measurements of KDP, the bending and stretching modes of the H-atom could be assigned.

A high energy-resolution neutron spectrometer with large mica mirrors, LAM-80ET, has been constructed at National Laboratory for High Energy Physics in Japan (KEK). The highest resolution achieved with this spectrometer is 1.2 µeV. In order to examine the capability of the spectrometer, the rotational tunnelling of the methyl group in 4-methyl pyridine N-oxide (N-oxy γ-picoline) has been measured. Using the (004) reflection of the mica mirrors, we have clearly observed four peaks at e=60, 115, 190 and 274 µeV. Measurements of the Q -dependence of these tunnelling peaks show that the tunnelling potential may be three-fold. It is also shown that the line width of tunnelling modes and the spin conversion at T >5 K are derived by the libron-phonon process with E L =30-40 K.

Proton diffusion was observed in Y-doped SrZrO 3 ceramics above 500°C by quasielastic neutron scattering. The line width of the quasielastic component varies with energy transfer Q and temperature. The temperature dependence is well elucidated by the thermal activation-type proton migration with activation energy of 0.2 eV. The observed hopping distance was 1.7 A, which is comparable to one of the distances between two proton sites.

Amyloid fibrils are filamentous protein aggregates that are found as deposits in patients with a range of human diseases including Alzheimer’s disease, Parkinson’s disease, and senile systemic amyloidosis. These abnormal protein aggregates and/or intermediate structures towards the mature fibrils are related to pathogenesis of these diseases. Elucidation of the mechanism of the amyloid fibril formation is thus important for elucidation of the mechanism of pathogenesis. Here we performed the elastic incoherent neutron scattering (EINS) measurements on hen egg-white lysozyme, a model protein of the amyloid fibril formation, under the monomer state and the amyloid fibril state. The values of the mean square displacement estimated from the EINS measurements and the force constant analysis of the temperature dependence of the mean square displacement showed that the protein under the amyloid state is more flexible than the monomer state, suggesting the correlation between the aberration in dynamics and the abe...

The paper describes developments of neutron scattering instruments in J-PARC neutron facility, which is a short pulse spallation source operated at a repetition rate 25 Hz and has a proton power 1 MW. New concept has been adopted to utilize high intensity coupled moderator even for a high resolution inelastic scattering instruments by taking a pulse shaping chopper system. Advanced technique has been also realized by taking an ability of event-recording system altogether with an improvement of a chopper system, realizing multi-Ei method. The paper also touches upon a general design concept for diffractometers in accordance with the source characteristics.

A Si-analyzer neutron backscattering spectrometer, DNA , in MLF is the first indirect geometry instrument which chooses the coupled moderator as a pulsed neutron source in addition with a high speed disc chopper as a pulse-shaping device, aiming for high energy resolution with high intensity. The pulse-shaping has the advantage of obtaining a variety of slit opening times. On the other hand, it has the disadvantage of limiting the wavelength band width measured within one pulse-shaped neutron beam. This disadvantage is solved by employing 4 slit discs on the pulse-shaping chopper and generating multiple pulse-shaped incident beams to realize efficient measuring, the so called Repetition Rate Multiplication: RRM technique. The automatic phasing procedure for the RRM technique is firstly discussed.

AMATERAS is a new disk-chopper-type spectrometer installed at Materials and Life Science Experimental Facility (MLF) of J-PARC. AMATERAS is equipped with an extra chopper for pulse shaping at the upstream position, in addition to a monochromating chopper, which conventional chopper spectrometers at pulsed source have. Owing to the use of these choppers and the high peak intensity from a coupled moderator source at MLF, the AMATERAS design realizes high-intensity and high-energy-resolution measurements in quasielastic and inelastic neutron scattering experiments. The spectrometer had the first neutron beam in May 2009. During the course of commissioning, the performance of the spectrometer was confirmed by conducting test experiments. AMATERAS is now open to users and is producing scientific outputs.

4SEASONS is a Fermi chopper spectrometer in operation at the Materials and Life Science Experimental Facility (MLF) in the Japan Proton Accelerator Research Complex (J-PARC). 4SEASONS is expected to facilitate high-efficiency measurements of weak inelastic signals on novel spin and lattice dynamics using thermal neutrons. The spectrometer is equipped with a coupled moderator and sophisticated components such as an elliptical converging neutron guide with high-critical-angle supermirrors, long (2.5 m) position-sensitive detectors, and a Fermi chopper appropriate for multiple-incident-energy (multi- E i ) measurements by the repetition-rate multiplication technique. Herein, we discuss in detail the design and performance of the spectrometer, and present some examples of the measurements obtained using this spectrometer.

We review our recent studies on glassy dynamics and glass transition of polymer thin films using neutron and X-ray reflectivity and inelastic neutron techniques. In the last decade extensive studies have been performed on polymer thin films to reveal very interesting but unusual properties such as reduction in the glass transition temperature T g with film thickness and negative thermal expansivity for thin films below about 25 nm, and often some contradictory experimental results have been reported. It is believed that a key to solve the controversial situation is to disclose heterogeneous structure or multi-layer structure in polymer thin films. In the review, therefore, we summarize our recent experimental results by neutron and X-ray reflectivity and inelastic neutron scattering, focusing on the dynamic heterogeneity in polymer thin films.

Neutron inelastic scattering of solid electrolyte β-Cu 2 Se was measured by the time-of-flight (TOF) method at room temperature. Low-lying dispersionless excitations near \(\hbar\omega\sim 3.4\) meV, which would be common to copper ion conductors, existed in the β-phase. This result was compared with those of the excitations in other solid electrolytes.

Neutron scattering measurements of the dynamical structure factor S ( Q , ω) of liquid Bi were carried out at 673 K in the range of the momentum transfer Q from 0.6 to 1.6 A -1 . Side peaks with the transfer energy less than about 8 meV were found in the S ( Q , ω) curves for \(Q \leqslant 1.2\) A -1 . They show a well defined dispersion curve which is connected with the dispersion line for small Q determined from the sound velocity. This indicates that the propagating collective excitations exist up to a relatively large momentum region even in the non-simple liquid metal as Bi.

The measurements of neutron TOF spectra of superionic conductor Ag 3 SI were carried out for its β-phase and quenched α-phase at room temperature. The spectra were analyzed by the use of a model function for the generalized density of states including a local vibrational mode and transverse acoustic modes. It was found that low energy excitations at \(\hbar{\omega}{\simeq}2\) meV existed not only in the β-phase but also in the quenched α-phase with α-AgI type structure. The narrow quasi-elastic central component due to the translational diffusion mode was also analyzed and the reasonable diffusion constants comparable with the known values of tonic conductivities were obtained.

Neutron diffuse scattering from powder samples of α-AgI type superionic conductors AgI, Ag 3 SI and Ag 2 S was measured using a triple-axis spectrometer with a fixed position of the energy analyzer so as to measure only the elastic scattering caused by a disordered distribution of cations. The disorder scattering curves thus obtained were analyzed under the assumption that Ag atoms distribute over crystallographic 12(d) sites among the bcc lattice formed by anions, and probability functions α n for a simultaneous occupation in the n-th neighbor sites were obtained. The results are discussed comparing with the pair correlation function g Ag–Ag ( r ) being obtained theoretically as well as by the analysis of X-ray diffuse scattering based on a liquid-like distribution model. The liquid phase of AgI was also studied by the same neutron technique and the results are discussed together with those for the solid phase.